1. Field of the Invention
The present invention relates to an optical signal analysis apparatus and an optical signal analysis method.
2. Description of the Related Art
Optical signal analysis methods are disclosed in, for example, Klaus Sch-tzel, “New Concept in Correlator Design”, Inst. Phys. Conf. Ser. No. 77, P175, 1985, Klaus Sch-tzel, “Noise on Multiple-Tau Photon Correlation Data”, SPIE Vol. 1430, P109, Photon Correlation Spectroscopy Multicomponent Systems, 1991, and Klaus Sch-tzel et al., “Photon Correlation Measurements at Large Lag Times”, Journal of Modern Optics, Vol. 35, No. 4, P711, 1988. In these optical signal analysis methods, an auto-correlation function or a cross-correlation function is estimated by using either the continuous measurement data (continuous measurement signal) of the intensity of fluorescence obtained from only one measurement point in one measurement or the plural-point time-series mixed data (multiple-point time-series mixed signal) measured while measurement points are repeatedly switched with time. As an analysis algorithm, a calculation technique based on a multiple τ scheme or a table retrieval scheme is available. When there is only one measurement point, an algorithm called a general scheme or a single measurement point multiple τ scheme is used. That is, the calculation technique based on the single measurement point multiple τ scheme estimates an auto-correlation function or a cross-correlation function at a measurement point through data processing such as channel calculation or data reconstruction. When measurement points are to be measured in one measurement, an algorithm called a general scheme or a table retrieval scheme is used. That is, the table retrieval scheme simultaneously estimates auto-correlation functions or cross-correlation functions for measurement points through high-speed data processing based on the time division of data at the respective measurement points and pieces of position information at the measurement points that are formed into a table.
Yoshiaki Horikawa, “For Single Molecular Fluorescence Analysis/Analysis on Single Biomolecular Interaction Using Statistical Analysis”, Bunko Kenkyu, Vol. 53, No. 3, 158-164, 2004 discloses a photo counting histogram method.
Kazuhiko Mase, Mitsuru Nagasono, Shinichiro Tanaka, and Shinichi Nagaoka, “Study of ion desorption induced by core-electron excitations of molecules on surface by using electron-ion coincidence spectroscopy”, Hoshasen, 10, 375-391, 1997 discloses a coincidence analysis method.
However, the purpose of estimating an auto-correlation function and a cross-correlation function at one measurement point is to observe molecular diffusion with a relatively low diffusion rate in a microscopic area. In actual application, when, for example, a molecule passes through the nuclear membrane of a cell, the molecular diffusion rate is low, and the diffusion time is long. It is impossible to observe the transmission of a signal, the influence of molecular movement in a given direction, and the like by auto-correlation and cross-correlation based on observation at only one point.
That is, according to the prior art, an observation area is limited to one measurement point (confocal volume). In addition, the movement of a molecule between two or more points cannot be observed. Furthermore, slow molecular diffusion cannot be observed.